1. Technical Field
Embodiments of the inventive concept relate to semiconductor memory devices and, more particularly, to three-dimensional (3D) semiconductor memory devices.
2. Discussion of Related Art
Semiconductor devices have been highly integrated to provide high performance and low costs. In particular, the integration density of semiconductor memory devices may directly affect the manufacturing costs of the semiconductor memory devices. Since an integration density of a conventional two-dimensional (2D) memory device is mainly determined by the size of the area occupied by a unit memory cell, its manufacturing cost may be greatly affected by a technique chosen to form fine patterns. However, since apparatuses used to form these fine patterns are extremely expensive, it may not be fiscally possible to increase the integration density of 2D memory devices beyond a certain threshold.
A 3D semiconductor memory device including memory cells three-dimensionally arranged has been developed to reach higher integration densities. For example, the number of cell memory electrodes and the number of metal interconnections connected to the cell memory electrodes have been increased to improve the integration density of the 3D semiconductor memory device. However, it is difficult to arrange a great number of these metal interconnections in the limited area provided by a 3D semiconductor memory device.